The 24-year old striker is on a season-long loan with the Terriers from Norwich City and Grayson suggests he may go after him on a less temporary contract after scoring two goals in five appearances in the Championship.
"Signing James in January is a possibility," Grayson told the Huddersfield Daily Examiner. "We've got him on loan until the end of the season anyway so that's an option.
"I've got a chairman who's willing to back me in the transfer market and he's done it previously.
"There's lots of options for us but we'll cross that bridge when we come to it.
"James is rightly flying with confidence. All he needed when we signed him in the summer was games under his belt. If he can have an injury-free season, he can be a major acquisition for us."